Transmission control switch



Sept. 25, 1951 L. D. BoYcE TRANSMISSION CONTROL SWITCH Filed June 21,1945 FIG.3.

INVENTOR LEONARD D. BOYCE FIG.2.

Patented Sept. 25, 1951 TRANSMISSION CONTROL swITcn Leonard D. Boyce,Maplewood, Mo., assignor to Carter Carburetor Corporation, St. Louis,Mo., a corporation of Delaware Application June 21, 1945, Serial No.600,722

1 Claim. l

This invention relates in general to control mechanism for automotiveengine transmission systems of the character embodying over-drivegearing and over-drive throw-out provisions enabling vehicle drivetransfer from over-drive to the manually controlled or more powerfultransmission gearing. The invention is concerned more particularly withimproved means for preventing operation of the over-drive throwoutduring vehicle travel at or in excess of a predetermined relatively highrate of speed, when over-drive throw-out, if permitted, would more orless seriously endanger the transmission gearing because of theresultant increased engine speed. This application is a continuation inpart of my co-pending application Serial No. 378,651,

filed February 12, 1941, now Patent No. 2,396,551.

In automotive engine transmission systems of the character aboveindicated, the over-drive is engaged automatically when the vehicleexceeds a. predetermined rate of travel. It is desirable to include inthe system, over-drive control provisions enabling ready transfer fromover-drive to a more powerful gearing when power and fast accelerationare required, as for example, in passing another vehicle on the road. Inone type of such control, a solenoid is energized in response tosubstantially full-opening of the engine throttle, to cause over-drivethrowout. However, it has been found in practice that the vehicle drivecannot be safely returned from over-drive to the third or high gear whenthe vehicle is traveling at or in excess of a predetermined rate ofspeed, as at or' above 45 miles per hour.

According, it is a general object of the present invention to provide animproved and highly effective means for preventing over-drive throwoutwhen the automotive vehicle is traveling at or above a predeterminedspeed, say 45 miles per hour. More specifically, the object of thisinvention is to afford in the control circuit of an over-drive throw-outsolenoid, a switch of the general character appearing in my beforementioned Patent No. 2,396,551, but embodying certainv improvementsthereover such as will increase the effectiveness of the switch toprevent 'solenoid energization and hence over-drive throw-out. whenbecause of the vehicle speed, it is not safe to transfer fromover-drive.

'A more detailed object is to provide a switch of the characterindicated, which is jointly controlled by the carburetor throttle valveand a device responsive to engine developed suction in the; carburetormixture conduit anterior to the throttle, the suction device beingsensitive to the (not.v shown) degree of suction developed inconsequence of engine operation at approximately the speed correspondingto vehicle travel at 45 miles per hour when it is undesirable tothrow-out the over-drive, such as to render the throttle controlineilective to close the switch, and wherein the switch mechanismaccording to the present improvements, includes novel and effectiveprovisions for causing a delayed or retarded response of the switch tothe throttle control when tne latter is actuated, whereby to permitcomplete operation or full response of the suction control under certainhereinafter defined conditions.

Other objects and advantages of the present invention will appearreadily from the following description of a presently preferredembodiment of the invention as illustrated in the accompanying drawing,in which:

Fig. 1 is a diagrammatic view showing portions of an automotive engineincluding the carburetor and transmission with the invention appliedthereto Fig. 2 is an enlarged sectional view of a part of the carburetorand the switch device according to the present invention, as taken online 2-2 in Fig. l;

Fig. 3 is a sectional view of the switch as in Fig. 2, but showing theswitch contacts engaged; and

Fig. 4 is a sectional view similar to Fig. 3, but showing the switchcontacts rendered ineffective to complete the over-drive throw-outcircuit.

With reference now to the drawing and first to Fig. 1 thereof, there isshown at I0 a portion of an internal combustion engine of automotivetype, including an intake manifold Il and carburetor indicated generallyat I2. A clutch and selectively controllable or change speedtransmission gearing of any suitable form, are located, respectively, inhousings I3 and I4 secured to the rear end of the engine I0. Thetransmission system includes an over-drive mechanlsm or gearing locatedwithin a housing Il attached to or forming a rearward extension ofhousing I4 and connected to a propeller shaft I6 of usual form,extending to a driving connection with the rear axle of the automotivevehicle A solenoid device I1 mounted on theover-drive housing l5,functions in a known manner upon energization of the solenoid thereof.to throw-out the over-drive, and hence to Shift vehicle drive from theover-drive gearing to the third or next higher and more powerful gearratio provided by the transmission gearing in housing |4. Control of thesolenoid |1 is presently effected by an electrical circuit whichincludes a battery |3 having one terminal grounded, as at |3, and aswitch device indicated generally at 23, mounted upon the carburetor l2.The battery and switch are connected to solenoid I1 by leads 2| and 22respectively, the latter being connected to an insulated terminal 23adapted to constitute the stationary contact of the switch 23 (Figs. 2,3 and 4).

The detailed construction of the solenoid device and that of theover-drive gearing and other parts of the transmission, are not hereillustrated, since such per se, form no part of the present invention.Although for present convenience, a manual shift lever 24 is shown forshifting the transmission gearing through the usual reverse, and first,second and third forward gears, it will be appreciated that suchshifting may be effected in any other suitable manner. Moreover and asis well known, the over-drive portion of the transmission system isautomatically engaged in response to a predetermined output speed of thetransmission, or in other words, when for example, the vehicle attains arate of travel of the order of 35 miles per hour.

The switch 20 as shown in detail by Figs. 2, 3 and 4, is of a characterto afford joint control thereof by the engine throttle and a suctioncontrol operative to render the switch ineffective to energize thesolenoid under predetermined suction conditions, as for the purposehereinbefore indicated. The structure of the switch includes an angularbody 33, the angularly related portions or legs of which are hollowed orlongitudinally bored as indicated at 3| and 32. Hollow leg 3| forms acylinder within which is slidably received a cup-shaped piston 33normally urged downwardly in the cylinder by a coiled spring 34, thelatter being engaged between the inner head surface of the piston and ashoulder 35 formed in the upper portion of the cylinder. A passage 33connects the cylinder above the piston, to the interior of thecarburetor mixture conduit preferably in the throat region of venturi 31(Fig. 2). Venting the cylinder space below piston 33, is a port 33 whichmay open to atmosphere or lead to the air inlet horn of the carburetor,as desired. Secured to the lower head surface of the piston 33 is anangular spring member or clip 33, the downwardly projecting leg of whichcarries a metallic ball or contact element 43 which comprises in effect,the movable contact element of the switch. Through clip 33, the contactelement 4|! normally or in its inactive position, is slightly spacedfrom the exposed inner end of the switch contact terminal 23 (Fig. 2).It is to be here noted that the body 33 of the switch is groundedthrough the carburetor,

intake manifold and engine block, and consequently in order to prevent adirect shunt of the switch contact elements 23 and 43, the piston 33 Laformed of a suitable insulating material, while contact-terminal 23 isspaced from the switch body 33 by a suitable insulating bushing 4|.Also, in order to prevent rotation of the piston 33 and so as tomaintain the ball contact 43 in proper alignment for engagement undercertain conditions, with the switch contact 23, piston 33 is providedwith an extension 42 suitably received in a guideway 43 in cylinder 3 I,the extension and guideway cooperating to determine non-rotative, linearmovement of the piston, as well as to limit the downward movement ofpiston 33 to that lum- 4 cient to align the ball contact 43 with contact23 (Fig. 2)

The hollow portion 32 of switch body 33, forms a second cylinder whichis separated from the cylinder formed by the hollow body portion 3|, bya wall 45. Slidably received in the second cylinder is a piston member43 provided with a forward projection 41 longitudinally bored as at 43.Piston projection 41 has its forward end received in an opening 43 inwall 4|, and is displaceable therethrough upon piston actuation in amanner presently to appear, for engagement with the ball contact 43 ofthe switch to move the contact to the left as viewed in Fig. 3. Suchmovement of the ball contact by projection 41, serves to determineengagement thereof with switch contact 23 or the adjacent exposed end ofinsulator bushing 4|, depending upon the positionment of the ballcontact by the suction responsive piston 33 in response to certainconditions of engine operation as will be presently described.

A pin 53 has one end thereof slidably received in the bore 43 of pistonprojection 41 and its opposite end portion extending longitudinallythrough a closure member 5| secured to the body portion 32 and closingthe end of the cylinder thereof. The pin 53 is urged outwardly or to theright as viewed in Fig. 2, by a coiled spring 52, while the piston 43and its projection 41 are urged in the same direction by a weaker spring53, so that a yieldable one-way connection thus results between theprojection or switch actuator 41 (and piston 43) and the pin 50.

A principal feature of the present invention is found in the presentprovision for causing a predetermined delayed or retarded response ofpiston 46 to actuation of the pin 53 in the direction to telescope itsinner end portion into the bore 43 of piston projection 41. Such pinactuation in the structure as thus far described, would serve to effectthrough the resulting compression of spring 52, inward displacement ofthe piston 43 and its projection 41, at a rate consequent only upon thecompression differential of springs 52 and 53. Under certain conditionsof engine operation to be related hereinafter, the almost immediateresponse of piston 43 may engage its projection 41 with ball contact 43to displace the latter against the contact 23 before the suction controlafforded by piston 33, can properly act to prevent such switch contact.Accordingly, the piston 43 rather tightly fits in chamber 54 to form adash pot connected to atmosphere by the restricted orifice 55. Thearrangement thus provides retarded movement of piston element 43 andhence a correspondingly retarded inward movement of switch actuatingprojection 41, to a degree determined in great part, by the calibratedport 55.

Pivotally mounted in the carburetor mixture conduit posterior to theventuri 31, is a butterfly throttle valve 33 which may be manuallyoperated in the usual manner, by means of a suitable arm 3| (shown inpart only) rigidly attached to throttle shaft 32. Formed on arm 3| is anextension 33 positioned to engage a stop 34 for determining the wideopen position of the throttle valve, while a second extension 35 of arm3| carries an adjustable screw 33 which through contact of its end 31with stop 34, determines the closed position of the throttle valve. Athird extension 33 of arm 3|, is provided for engagement with theexposed end of pin 50 when the throttle valve le substantially fullyopened (me.

3 and 4), to displace the pin and thereby piston 46 and extension 41,inwardly so as to engage the latter with ball contact 40 and urge thecontact in the direction of contact 23.

With further reference to the suction control, spring 34 is adjusted soas to maintain the piston 33 in its lowermost position, as in Fig. 3,when the suction at the throat of venturi 31 is less than approximately1.8 inches of mercury, which corresponds with a vehicle speed ofapproximately 45 miles per h-our. When this degree of suction isexceeded at the Venturi throat, attendant upon a rate of vehicle travelin excess of 45 miles per hour, piston 33 will respond upwardly againstspring 34, to a position of engagement with a shoulder 1l) formed in awall of cylinder 3i, whereby to raise the ball contact 40 to a position(Fig. 4) wherein it cannot engage the contact 23.

In operation, when the transmission is in overdrive and the vehiclespeed is less than 45 miles per hour, the elements of the switch devicewill assume the relative positions shown in Fig. 2, so long as thethrottle is not operated to its fullopen position. Assuming now a demandfor transmission shift from over-drive to a more powerful gear ratio,whereby to afford increased power and fast acceleration, the throttle isoperated to approximately full open position so as to engage extension68 with the pin 50 to displace the latter against its spring 52. Inconsequence thereof and as hereinbefore described, the extension oractuator element 41 will respond by inward movement retarded however, bythe action of the pneumatic device constituted as herein described, butnevertheless ultimately effecting through the extension 41, engagementof the ball contact 40 with contact 23, whereby the circuit to thesolenoid i1 will be completed to cause operation thereof to throw-outthe over-drive. In the presence of such demand when the vehicle speed issubstantially in excess of 45 miles an hour, throttle operation of theswitch device in an attempt to throw-out the over-drive, will beineffective to produce this result, because under this condition thesuction control normally will have fully responded in a manner to liftthe ball contact 40 out of registry with contact 23, so thatdisplacement thereof by the piston extension 41 will engage the ballcontact only with the exposed end of the insulator bushing 4I (Fig. 4).However, upon throttle operation of the switch as the vehicle speedbecomes approximately equal to or tends to exceed only slightly thepredetermined rate of 45 miles an hour, the present novel provision fordelaying or retarding switch closing movement of the piston extension oractuator element 41, serves effectively to prevent entrapment of theball contact 40 in a position of contact with switch element 23 beforethe suction device can operate fully, to lift or retract the ballcontact. Such delay as before indicated, is afforded by the pneumaticdevice comprising piston 43 in chamber 54 and the associated calibratedvent port 55,v which determines the displacement rate of the piston 46in the switch-operating direction, according to the rate of airdischarge from the chamber through port 55 as predetermined by the portarea. Thus through the port 55, the rate of movement of the switchactuator element 41 may be selected so as to assure a suilicientlydelayed operation of the switch such as to afford under the foregoingconditions, a full response of the suction device to position the ballcontact out of registry with the contact 23. Moreover, if while thevehicle is traveling at the critical speed, as miles an hour accordingto the presently selected example, there is a tendency for the vehiclespeed to fall slightly below the critical at the moment the throttle isfully opened to produce switch operation, the present retardation offinal switch actuation is equally effective to allow sufficient time forthe spring 34 to move the suction piston 33 to its lower limit, wherebyto align the ball contact 40 with the contact 23, for permittingultimate switch closure and consequent solenoid energization to effectover-drive throw-out. It is to be noted also that the delayed orretarded actuation of the switch is of particular advantage in the eventthe suction piston 33 should become momentarily stuck when conditionsdemand its movement in response either to suction above the criticalvalue of 1.8 inches of mercury, or to the return spring 34 when thesuction is below the critical value, since if the throttle is fullyopened at such time, engagement of the ball contact 40 by pistonprojection 41 will be sufliciently delayed to permit final positioningof the contact, providing of course, that the sticking of the piston 33is only relatively momentary.

From the foregoing it now will appear that the present improvementsprovide a highly effective over-drive throw-out control switch mechanismwhich functions to cause transmission shift from over-drive upon demandtherefor when the vehicle speed is below the indicated critical speed;to prevent such shift when the vehicle speed is in excess of thecritical, andv to enable a full response of the suction control thereofeither to prevent over-drive throw-out when the vehicle speed isapproximately equal to or tends to exceed only slightly the criticalspeed, or to permit throw-out when the vehicle speed tends to dropslightly below the critical speed.

The invention may be modified in various respects as will occur to thoseskilled in the art, and the exclusive use of all such modifications ascome within the scope of the appended claim is contemplated.

I claim:

In combination with an internal combustion engine intake conduit, acontrol switch including a body having a pair of chambers, one of saidchambers having a pressure connection to said conduit, a pressureresponsive device in said chamber operatively associated with saidswitch for effecting the operation thereof, a switch actuating plungerextending into the other chamber, an element on said plunger closelyfitting said chamber for trapping a. body of fiuid therein, said secondchamber and said element forming a dashpot contributing to coordinatedaction of said pressure responsive device and said plunger, and yieldingmeans to move said plunger for operating said switch.

LEONARD D. BOYCE.

REFERENCES CITED The following references are of record in the file ofthis patent:

. `UNITED STATES PATENTS

